The reproductive comparisions of three species of MIllepora

• Main Authors: Cho, Li Ching, 卓麗卿
• Other Authors: Soong, Keryea
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/35827976708657366311

碩士 === 國立中山大學 === 海洋生物研究所 === 84 === This research, on the reproduction of three species of Millepora (plate, branch, fork form) at Hengchun Peninsula, was conducted between February, 1994 and July, 1995. In order to understand possible prezygotic isolation between them, I investigated reproductive periods, reproductive characters as well as the roles and functions of medusae in the life history of Millepora. The medusa release of all three species of Millepora occurs between April and May. They might have up to 4 bouts during this period, each lasting 1~3 nights. The first medusa appear before dusk, although more were accumulated after sun-set. Dates of medusae release of the three growth forms of Millepora at the same site seldom overlaps. The probability of finding synchronously releasing colonies is much lower between species than within species. And in branch form Millepora, the probabiliy of finding synchronously releasing colonies is much lower between area than within area. No differences in size and shape of medusae and gametes characters were found among the three species of Millepora, although there is difference in sizes of nematocysts. To sum up, there is large degree of prezygotic isolations among the three species of Millepora. The medusa have strong negative geotaxic and weak negative phototaxic behaviour. The character might facilitate their aggregation, thus increase fertilization rate. The distribution of medusae on the colony is not even, with very low densities on the margin of the colony, but high densities on the middle portion. Medusa release in Millepora is affected by light and their sex. Male medusae were released prior to females; while dark treatment delayed the release of male and female medusae.